Electrical gas discharge tube circuits



y 1957 J. H. BEESLEY 2,799,806

ELECTRICAL GAS DISCHARGE TUBE'CIRCUITS Filed 001;. 6, 1954 2 Sheets-Sheet 1 FIG. 1.

H TT'OR HEY July 16, 1957 J. H. BEESLEY 2,799,806

ELECTRICAL GAS DISCHARGE TUBE CIRCUITS Filed Oct. 6, 1954 2 Sheets-Sheet 2 lNvEuToR C/OHA/ HENRY Be 654 E) EY% A HTTpRNEY nite States Free ELECTRTCAL GAS DiSCi-IARGE TUBE CRCUITS John Henry Beesiey, Coventry, England, assignor to The General Electric Company Limited, London, England Application October 6, 1954, Serial No. 4643,6538

7 Claims. (Cl. 315166) This invention relates to electrical circuits employing gas discharge tubes of the kind having at least an anode, a cathode and a trigger electrode. The invention is more particularly but not exclusively concerned with such circuits in which cold cathode gas discharge triodes are employed.

It is an object of the present invention to provide improved electrical gas discharge tube circuits in which combinations of electrical signals that are applied to groups of input leads may be translated each into a single electrical signal occurring on one of a plurality of output leads, the output lead on which such a signal occurs being characteristic of the signal combination from which it was derived.

According to the present invention, an electrical gas discharge tube circuit comprises a plurality of gas discharge tubes which are of the kind having at least an anode, a cathode, and a trigger electrode and which are arranged in groups, each of the said gas discharge tubes having associated therewith means for deriving a voltage signal from the discharge current through the tube when a discharge exists between its anode and cathode, a plurality of paths to which the said voltage signals are applied, a plurality of output leads, and means connecting the said paths to the said output leads so that a signal occurs on an output lead only when voltage signals are applied to the said paths upon a particular combination of the said discharge tubes, one in each group, being conducting, the output lead on which such a signal occurs being characteristic of the said combination from which the signal was derived.

According to a feature of the present invention, means are provided for inhibiting the striking across its anode to cathode discharge gap of any tube of at least one group of gas tubes until an anode to cathode discharge exists in a gas tube of the remaining group or of each of the remaining groups of gas discharge tubes.

Preferably, the connections between the paths which are associated with the gas discharge tubes of one group and the said output leads are made via resistive elements such as resistors and the connections between the paths which are associated with the gas discharge tubes of the remaining group or each of the remaining groups are made via rectifiers which are so connected as to be nonconductive to the said voltage signals.

With such an arrangement, means may be provided for ensuring that an anode to cathode discharge exists in a gas tube of each group of gas tubes that are associated with paths having rectifier connections to the output leads before such a discharge can occur in a gas tube of the group of gas tubes which are associated with paths having resistor connections to the output leads.

One example of a gas discharge tube circuit in accordance with the present invention will now be described with reference to the two figures of the accompanying diagrammatic drawings which are complementary illustrations of the electrical circuit of an electrical signal translating device.

Referring now to Figures 1 and 2, the circuit there shown comprises a plurality of cold cathode gas discharge triodes. Each of these triodes has its anode 10 connected to a terminal 13 which is maintained at a positive potential with respect to earth. This potential is of such a value that when a discharge exists between the trigger electrode 12 and the cathode 11 of a gas triode the said gas triode strikes by transfer of this discharge to its anode to cathode gap. Each of the gas triodes has its cathode 11 connected to earth by way of a resistor, the value of each of these resistors being such that when a gas triode is conducting the voltage developed across its associated resistor by virtue of the discharge current is of sufiicient amplitude to initiate a trigger electrode to cathode discharge in any other gas triode when applied between these electrodes.

The gas triodes 14 to 22 are arranged in three groups A, B and C there being three gas triodes in each group. These gas triodes are each associated with a difierent one of the input leads 1 to 9 and with up to nine difierent paths such as the paths 71 to 76, of which only three are shown in each case. The paths, such as the paths 71, 72 and 73, associated with the gas triodes of groups A and B are connected by way of rectifiers, such as the rectifiers 60, 61 and 62, to up to twenty-seven difierent output leads of which only the nine leads 45 to 53 are shown and the paths, such as the paths 74, and 76, associated with the gas triodes of group C are connected by way of resistors, such as the resistors 57, 58 and 59, each to a different one of the output leads. Each of the said output leads is thus associated with a different combination of the said gas triodes, one in each of the groups A, B and C, and with another gas triode, the leads 45 to 53 for example being associated with the gas triodes 23 to 31 respectively.

Three gas triodes 32, 33 and 34 are associated with the groups A, B and C respectively. It is arranged that on any one of the gas triodes 14, 15 or 16 of group A strik ing a discharge is initiated across the trigger electrode to cathode gap of the gas triode 32 which consequently strikes by virtue of the potential on its anode. Similarly the striking of any one of the gas triodes 17, 18 and 19 of group B initiates the striking of gas triode 33. The cathodes of gas triodes 32 and 33 are connected by way of leads 35 and 36 and resistor 37 and rectifier 38 respectively to the trigger electrode circuit of gas triode 34. On the gas triode 32 striking the positive voltage developed across its cathode resistor 39 is applied across the resistor 37, rectifier 38 and the cathode resistor 40 of the gas triode 33 in series. In the absence of an anode to cathode discharge in the gas triode 33 the rectifier 38 is conducting and the voltage that is applied to the trigger electrode circuit of the gas triode 34 is insufiicient to initiate the striking of this tube. When both of the gas tridoes 32 and 33 are struck the rectifier 38 is so biassed as to be non-conducting and the voltage that is applied to the trigger electrode circuit of the gas triode 34 is then sufficient to initiate the striking of this tube.

in order to prevent the striking of one of the gas triodes 2t), 21 or 22 in group C until a gas triode is struck in each of the groups A and B the rectifiers 41, 42 and 43 are each connected between a different one of the input leads 7, 8 and 9 and the cathode 11 of the gas triode 34. When the gas triode 34 is conducting the voltage developed across its cathode resistor 44 biases each of the rectifiers 41, 42 and 43 so as to be non-conducting and the application of a suitable positive voltage signal to any one of the input leads 7, 8 or 9 will result in the appropriate one or" the gas triodes 20, 21 and 22 striking. In the absence of anode to cathode discharge in the gas triode 34 positive voltage signals on the leads 7, 8 and 9 will leak away over the 3 rectifiers 41, 42 and 43 and the resistor 44 to earth.

The operation of the circuit shown in Figures 1 and positive voltage signal at the cathode 11 of the approipriate one of the gas triodes 23 to 31, each of the said a signal combinations being such as to result in the striking of one gas discharge triode in each of the three groups :A,BandC. 7

"leads 2, and 8f the positive voltage on lead 2 initiates.

'Assumingjthat none of the gas discharge triodes are' initially struck and that suitable voltage signals, which are; positive with respect to earth, are applied to one input lead of each of the groups A, B and C such as the a" discharge between the trigger electrode and cathodeof' the gas triode 15. On the gas triode striking its cathode attains a positive voltage with respect to earth by virtue of the discharge current flowing through resistor 54. This voltage is applied'over rectifier 55 to i the trigger electrode 12 of gas triode 32 and initiates the Striking of this triode. In a similar manner the positive voltage on lead 5 initiates the striking of gas triode 18 which in turn initiates the striking of gas triode 33. As previously described when both of the gas triodes 32 and v 33 are conducting across their anode to cathode gaps, the

gas triode 34 strikes.

resistor 54, of gas triode 15. p is developed across this resistor 54 may be of such a I value as to prevent the initiation of a trigger electrode The voltage developed across the resistor 44 biases rectifiers 41, 42 and 43 so as to benonconducting and the positive voltage that is applied to lead 8 can now initiate the striking of gas triode. 21.

Had the appropriate gas triodes of groups A, B and C been allowed to strike in any random order; then assuming the gas triode 21 of group C to strike first, its discharge current is shared between the cathode resistor 56 and each of the asociated paths. Consider the output leads 48, 49 and 50. Part of the said discharge current that flows to these leads over resistors 57, 58 and 59 is supplied over rectifiers 60, 61 and 62 to the cathode The resulting voltage that to cathode discharge in gas triode 15 on the application 'of a positive voltage signal to the input lead 2 and so j prevent the striking of gas triode 15. Similarly if nine different paths, like the paths 74, 75 and 76,. are associated with each gas triode 20, 21 and 22 of group C, the striking of anyone of these triodes will result in a 7 positive voltage at the cathode of each of the gas triodes 14 to 19 of groups A and B. As described above, these voltages may be each of sufiicient value to prevent the initiation of a trigger electrode to cathode discharge in V the gas triodes 14 to 19 on the application of positive f voltage signals to any of the input leads 1 to 6.

Onalljthree of the gas triodes 15, 1 8 and 21 being struck, the positive voltages occurring at their cathodes by virtue of the discharge currents flowing through the resistors 54, 63 and 56 respectively are each applied to 6 the associated paths which include the paths 71 to 76. The output leads 45 to 53 and the like (not shown) are output leads, such as the leads 45 to 53, which is associated with all three of the struck triodes. In the case under consideration this is output lead 49. The positive voltage at the cathode of gas triode 21 is applied to the lead 49 over'resistor' 58. iThe corresponding positive voltages on the cathodes. of gas triodes 15 and 18 are applied to theirectifiersol and 64 which are thus biased so as to be non-conducting. None of the remaining output leads which are associated with gas triode 21 have 4 both of their associated rectifiers, like the rectifier 60 for example, thus biased with the result that the voltages which are applied to these leads are also applied to one or more shunt paths, each such path comprising in series a rectifier such as the rectifier 65 and a resistor such as the resistor 66 of the gas triode 19. The positive voltage that is applied to the output lead 49 is of sufi'icient amplitude to initiate the striking of the associated gas triode 27. On the gas triode 27 striking the terminal 68, which is connected to the cathode of this triode, attains a positive voltage in respect to earth by virtue of the discharge current flowing through resistor 67 The positive voltage signals that were applied to the input leads 2, 5 and 8 have'thus been translated into and are charac- 7 may also be applied to other cases.

terised by a single positive signal on the terminal 68.

In order to make the circuit available for use in a subsequent signal translating process it may be arranged that when a signal representing a translation is no longer required the positive potential that is supplied to 'the terminals 13 is discontinued or'so reduced in value for such a'period in time as to result'in the extinction of all the said gas triodes previously struck.

Although the invention has been described in connectiorrwith the use of three groups of gas discharge tubes, it Thus if two groups of gas tubes are employed, the connections between the paths that are associated with the gas tubes of one group and the output leads may be made via resistors, the corresponding connections ,for the gas tubes of the other group being made by means of rectifiers. Again, if more than three groups of gas tubes are employed it is preferred that only the connections between the paths that are associated with the gas tubes of one group and the output leads shall be made via resistors. In any of the above cases it should be arranged that a gas tube of the group which is associated with the said resistor is prevented from striking in response to a suitable voltage signal on the appropriate one of the associated input leads until at least one of the gas tubes in each of the remaining groups is struck. V V V I V The number of gas tubes which are provided in each of the groups A, B and C may also be varied, such variations being within the scope of the present invention. Thus an electrical circuit of the kind described above may be em- 4'- ployed to provide signal translating facilities in a translator of the kind used in automatic telephone systems.

As is well known a translator of this kind may be employed to translate combinations of signals, each signal 7 representing a digit dialled by a calling subscriber, into a form that is suitable for establishing a speech current path between the telephone exchange of the calling subscriber and the exchange of the wanted subscriber over a predetermined route. 7 V

In such an application it is known to store the first three digits dialled by a subscriber on three groups of storage devices, so called registers, a suitable storage device bein g-a gas discharge tube counting chain. Such storage may either be numerical, that is one gas tube struck out of ten there being a diiferent group of ten gas 0 tubes for each digit to be stored, or in the form of a code tubes for each digit to be stored. The method of storage forms no part of the present invention, the only requirernent being that each of the three storage devices shall provide a positive voltage signal on one of a group of ten leads, there being a different group of ten leads for each The ten leads from each of the storage devices are connected each to a different input lead of a corresponding group in the translating device. Since signal translating facilities are required for three digits each digit having ten possible values one thousand output leads will be required and each of the gas discharge tubes will be associated with a hundred paths.

I claim:

1. An electrical signal translating circuit comprising a plurality of first gas discharge tubes which are arranged in groups and which are operable in combinations of one gas discharge tube from each group, a plurality of second gas discharge tubes one for each said combination, means which comprises a difierent first coincidence gating circuit for each of said combinations and which is responsive to the operation of the first gas tubes according to any one of said combinations to operate the second gas tube that corresponds to the combination, and a second coincidence gating circuit to inhibit the operation of any gas tube of a predetermined one of said groups until one gas tube in each of the remaining groups is operated.

2. An electrical signal translating circuit according to claim 1 in which said second gating circuit comprises a third gas discharge tube, means connected between the first gas tubes of said predetermined group and the third gas tube to prevent the operation of any gas tube of said predetermined group until said third gas tube is operated, a diiferent fourth gas discharge tube for each of said remaining groups, means responsive to the operation of any of the first gas tubes of a remaining group to operate the fourth gas tube of that group, and means responsive to the operation of all the said fourth gas tubes to operate said third gas tube.

3. An electrical signal translating circuit according to claim 2 in which the first, second, third and fourth gas discharge tubes are cold cathode gas discharge triodes.

4. An electrical signal translating circuit according to claim 1 in which each of said first gas tubes has individual resistance means connected in series with its anode to cathode discharge gap to derive a first voltage signal from the discharge current that flows across said gap when the first gas tube is operated.

5. An electrical signal translating circuit according to claim 4 in which each of said second coincidence signal gating circuits comprises a first input path comprising resistance connected between the resistance means of a first gas tube of said predetermined group and a common point to apply the first voltage that is derived upon the operation of that first gas tube to the common point, a different second input path for each of said remaining groups, a second input path comprising 'a rectifier connected between the resistance means of a first gas tube of a remaining group and the common point to apply the first voltage signal that is derived upon the operation of that first gas tube to the rectifier which is not conductive thereto, and an output path connected between the common point and one of said second gas tubes to operate that second gas tube from the voltage signal that occurs at said common point when first voltage signals occur simultaneously on said first input path and each of said second input paths.

6. An electrical signal translating circuit according to claim 1 in which each of said second gas tubes has individual resistance means connected in series With its anode to cathode discharge gap to derive an output voltage signal from the discharge current that flows across the said gap when the second gas tube is operated, an output terminal, and a path connecting the output terminal to the resistance means to apply the output voltage signal to said terminal.

7. An electrical signal translating circuit comprising a a plurality of first cold cathode gas discharge triodes which are arranged in groups and which are operable in combination of one gas discharge triode from each group, resistance means individual to each said gas triode to derive a first voltage signal from the current that flows when the gas triode is operated, a plurality of first coincidence signal gating circuits each comprising a difierent input for each said group and an output, a plurality of paths to apply the first voltage signals to the inputs of the first coincidence signal gating circuits, each said gating circuit being connected by said paths to a different combination of said first gas triodes comprising one from each group and being responsive to the first voltage signals that occur upon the operation of all the first gas triodes of its combination to apply a second voltage signal to its output, a plurality of second cold cathode gas discharge triodes, a plurality of paths connecting the outputs of said first gating circuits each to a different one of said second gas triodes to apply the second signal resulting from the operation of a combination of said first gas triodes to operate the second gas triode corresponding to the combination, a third cold cathode gas discharge triode, paths connecting the first gas triodes of a predetermined group to the third gas triode to inhibit the operation of any of the first gas triodes of said predetermined group until said third gas triode is operated, a difierent fourth cold cathode gas discharge triode for each of the remaining groups, paths connecting the first gas triodes of each remaining group to the fourth gas triode of that group to operate said fourth gas triodes each in response to the operation of any first gas triode of its group, and paths connecting said fourth gas triodes to said third gas triode to operate said third gas triodeonly when each of said fourth gas triodes is operated.

References Cited in the file of this patent UNITED STATES PATENTS 2,637,017 Holden Aug. 28, 1953 2,668,931 Hall et al. Feb. 9, 1954 2,678,409 Holden May 11, 1954 2,709,771 Dehn May 31, 1955 

